The objective of this research is to lipid-extract selectively the hydrophobic membrane proteins from lymphocyte target cell plasma membrane preparations and reconstitute these proteins into lipid vesicles of known composition. There is a great deal of evidence that the histocompatibility antigens of the mouse, H-2K and H-2D, are hydrophobic intrinsic membrane proteins which are involved in the recognition of target cells by primed cytotoxic T cells. The specific goals of this research are 1) to determine the mechanism of inhbition of conjugate formation by target cell plasma membranes, 2) to lipid extract and reconstitute the recognition molecules from the target cell membrane, 3) to characterize physically and immunologically in a functional assay the reconstituted proteins, 4) to develop a fluorescent, cell-mediated cytotoxicity assay for inhibition of killing by target cell plasma membranes, 5) to induce cytotoxic T cells in vivo by priming with vesicles of known physical state and chemical composition, and 6) to determine the physical state required for cellular recognition for reconstituted proteins in lipid vesicles. The methods to be employed in this study include differential and sucrose gradient centrifugation, fluorescence and phase-contrast microscopy, two-dimensional gel electrophoresis, and electron paramagnetic resonance spectroscopy.